【作者】 孔维涛；

【导师】 张庆范；

【作者基本信息】 山东大学 ， 电力电子与电力传动， 2009， 博士

【摘要】 绕组励磁同步电机具有功率因数可调、效率高等优点,在工业大功率场合获得了广泛应用,因此研究和开发高性能的绕组励磁同步电机驱动系统具有重大的经济价值和社会效益。目前开发高性能绕组励磁同步电机驱动系统所采用的控制方案主要有两种:一种是直接转矩控制(DTC);另一种是磁场定向矢量控制(FOC)。绕组励磁同步电机的矢量控制策略具有控制结构简单,物理概念清晰,电流、转矩波动小,转速响应迅速,易实现数字控制等优点。因此,在交流传动领域中,越来越受到学者的关注。但是,无论在国内还是国外,交直交型绕组励磁同步电机矢量控制系统的研究还缺乏全面深入的理论研究,还没有建造起矢量控制系统的理论体系构架。本文对绕组励磁同步电机矢量控制系统进行了初步的理论探讨,并进行了详细的实践研究,为以后更深入、广泛地研究此系统,打好坚实的基础。本论文主要研究内容如下:通过广泛的查找文献,对几种常见的同步电机传动系统进行了综述,分析了同步电机变频调速原理,在此基础上,讲述了无传感器技术在同步电机中的应用现状。无传感器技术主要有两大类:基于基波量的检测方法和基于外加信号的激励法。随后,对转子初始位置的估计进行了综述,其方法有:基于电机定子铁芯饱和效应的转子位置估计,高频信号注入法,基于定子绕组感应电压的估计法和基于相电感计算法等。绕组励磁同步电机转子初始位置估计的研究还很少。对绕组励磁同步电机矢量控制的理论进行了全面深入地研究,建立起矢量控制的理论体系构架。首先,基于磁势等效原理,将三相静止交流信号等效变换为两相旋转直流信号,将交流电机等效为直流电机进行控制。在Clarke变换和Park变换的基础上,得到凸极同步电机转子磁场定向的电压矩阵方程、功率方程和运动方程。根据上述方程,绘出dq轴的等值电路及矢量图,得到状态空间描述的dq轴数学模型。其次,根据模型参考自适应原理,对同步电机转速进行估计。忽略同步电机d轴阻尼绕组的作用,取同步转速为零,得到同步电机αβ静止坐标系下的数学模型。将不含有转子转速信息的方程作为参考模型,将含有转速参数的方程作为可调模型,根据波波夫超稳定性和正性原理,对转子转速进行估计。最后,根据模型参考自适应估计的转子转速,设计磁通观测器来估计转子磁通,实现磁通反馈闭环控制。磁通观测器采用降维观测器,仅对转子磁通分量进行重构,并通过极点配置算法,合理配置观测器的极点,使观测器满足系统的性能指标,达到磁通观测的目的。新颖的空间矢量脉宽调制算法。从空间矢量的基本概念入手,深入分析了定子三相对称电压与空间电压矢量之间的关系。由三相电压源型逆变器输出电压波形得到六个有效开关状态矢量,这六个开关矢量和两个零矢量合成一组等幅不同相的电压空间矢量,去逼近圆形旋转磁场。其次,根据空间电压矢量所在的扇区,选择相邻有效开关矢量,在伏秒平衡的法则下,计算各有效开关矢量的作用时间。并且,探讨了扇区判断和扇区过渡问题,定性分析了空间矢量脉宽调制(SVPWM)的性能。最后,根据每个扇区中开关矢量作用时间,采用软件构造法,在TMS320LF2407A硬件上实现了SVPWM。实验结果表明,该算法简单易实现,能够有效的提高直流母线的电压利用率,具有在低频运行稳定,逆变器输出电流正弦度好等优点。空间矢量过调制算法的研究。在上述线性调制的基础上,提出一种基于电压空间矢量的过调制方法。过调制区域根据调制度分成两种不同的模式,分别为模式Ⅰ(0.907＜m≤0.952)和模式Ⅱ(0.952＜m≤1),然后,深入分析了两种过调制模式的调制特点和实现原理。当参考电压矢量位于过调制模式Ⅰ时,其轨迹位于六边形内部的部分仍保持为圆形,其幅值略大于参考电压矢量的模值,以补偿空间矢量在六边形边上的电压损失;在六边形之外的圆形轨迹变为六边形的边沿,此区域内,电压空间矢量的幅值扭曲,相位连续。当参考电压矢量位于过调制模式Ⅱ时,实际的电压空间矢量的轨迹不再是圆形,而是在六边形顶点处保持一定的时间后沿着六边形的边沿运动,此时,电压空间矢量的幅值扭曲,相角离散,在六边形顶点处存在保持角。根据上述原理得到过调制模式Ⅰ的六扇区计算公式,并在TMS320LF2407A硬件上进行实验,证明了过调制算法的可行性。基于定子电流矢量的死区补偿方法。分析了逆变器死区效应产生的原理,以及它对逆变器输出电压的影响,提出一种根据定子电流矢量所在扇区补偿偏差电压的方法。该方法检测两相定子电流,经过有限冲击响应(FIR)数字滤波器滤波后,得到静止坐标系下αβ轴上的分量,根据αβ轴分量合成定子电流矢量,计算电流矢量的相角,判断其所在的扇区,得到三相电流的极性,从而确定补偿电压矢量的大小和方向。通过仿真和实验,证明了所提死区补偿方法的正确性和可行性。最后,对本文所作的工作进行了总结,阐明了本文的研究成果,并指出了本课题需要进一步研究的内容。更多还原

【Abstract】 Winding excited synchronous motor (ESM) has many advantages of adjustable power factor and high efficiency, so it has been widely applied in high power apparatus. It is of great economic value and social effects for researching and developing high performance driving system of excited synchronous motor. Recently, there are mainly two control schemes used to develop high performance ESM drive system: one is direct torque control (DTC), and the other is field orientation control (FOC). Field orientation control of ESM has many merits: its control structure is very simple, the physical concepts is clear, the fluctuation of current and torque is little, the response of speed is rapid, and control strategy is easy to digitization. So, more and more people pay attention to this method in AC drive fields. However, research of vector control system about ac-dc-ac excited synchronous motor lacks full and in-depth study. The theory of vector control system has not been constructed. This paper discusses the primary theory of excited synchronous motor and carries out the practice study in detail. And then solid foundations are completed for researching the system more depth and widely in the future. This thesis has mainly the following aspects:Above all, several familiar synchronous drive systems are reviewed, and the principle of variable voltage at variable frequency about synchronous motor is analyzed. Based on this theory, the application of sesorless schemes in synchronous motor is described, and the sensorless technology is classified into two kinds. One is based on the fundamental variables, and the other is based on external exciting signal. Then the estimation methods of the initial rotor position are reviewed and these methods can be classified as: basing on the saturate effect of motor magnetic circuit, high frequency signal injection, induced voltage of stator windings, and the calculation of stator inductance etc. There are few papers investigating ESM initial rotor position estimation.Vector control theory of excited synchronous motor is studied in detail and the control structure is built up. First, three phase stationary ac signals are transformed equivalently into two phase rotated dc signals and ac motor is controlled to act as dc motor. Then voltage matrix equation, power equation and motion equation of field oriented control of salient pole synchronous motor are obtained based on Clarke and Park transformation. According to above equations, the equivalent circuits and vector diagram in dq axis are plotted out and mathematical models described by state space in dq axis are constructed.Second, according to model reference adaptive control theory, the speed of synchronous motor is estimated. Neglecting the effect of damper windings in d axis and taking the synchronous speed equal to zero, the mathematical models ofsynchronous motor inαβstationary reference frame is obtained. The equationwithout speed information is acted as reference model and the equation with speed parameter is acted as adjustable model. The rotor speed is estimated in terms of Povpov’s hyperstability criterion and positive theory.Then a flux observer is designed to estimate the rotor flux according to the rotor speed identified by model reference adaptive system and realize closed-loop control of feedback flux. A reduced order state observer is adopted to reconstruct the rotor flux component, and the poles of flux observer are assigned properly by pole assignment algorithm to satisfy the performance criteria of system and to get the purpose of observing flux.To start with the basis concept of space vector, the paper analyzes the relationship of stator phase voltages and voltage vectors in space. Six active switching state vectors come from the inverter output voltages. These six active switching vectors and two zero vectors compose a set of voltage space vectors with same amplitude in different phase to approach circle rotating flux. Second, . according to the sector of voltage space vectors, adjacent switching state vectors are selected to calculate on-durations under volt-second balance principle. The questions of judging sectors and sector transition are discussed and qualitative analysis of performance is carried out. At last, an experiment is carried out according to the time duration by means of software construction method.According to the linear modulation, an overmodulation technology based on voltage space vector is proposed. The overmodulation area subdivide into two different mode by modulation index, one is mode I (0.907 < m≤0.952) and the other is mode II (0.952 < m≤1). Then the modulation character and realize theory of two overmodulation mode are analyzed in depth. When the voltage space vector is located within overmodulation mode I, the locus in the hexagon remain the circular, but the amplitude is larger than the modulus of voltage space vector to compensate the voltage distortion on the edge of hexagon; the reference voltage vector tracks the hexagon sides in the remaining. In this field the amplitude of voltage space vector is distorted and phase angle is continuous. When the voltage space vector is in the overmodulation II, the reference voltage is no longer tracking the circle of radius and holds an angle at the vertex and then moves along the hexagon. In this mode, the amplitude of voltage vector is distorted and phase angle is discrete. There is a holding angle at the vertex of hexagon. The computational formulas of six sectors in mode I are derived from above theory and an experiment is carried out on the TMS320LF2407A. The results demonstrate the overmodulation algorithm feasible.The principle about dead-time effect of inverter is clarified. And then a method to compensate voltage deviation based on the phase current polarity is proposed to improve the inverter output voltage. In this method, two stator phase currents aredetected and the components ofαβaxis in stationary coordinate plane are obtained through a finite impulse response digital filter. The stator current vector is synthesized based on theαβcomponents and the sector that current vector islocated in is judged by calculating the phase angle of current vector. Then according to polarity of three phase currents, the magnitude and direction of compensated voltage vector is determinate. The validity and feasibility of dead time compensation is proved through simulation and experiment.At last, a summary is made about the work of this paper and states the researching achievement. The content that needs further studies on this project is pointed out.更多还原